Background Tasks

Use q.run() to execute functions in the background, in-process.

import time

import random

from h2o_wave import main, app, Q, ui

def blocking_function(secs) -> str:

time.sleep(secs) # Blocks!

return f'Done waiting for {secs} seconds!'

@app('/demo')

async def serve(q: Q):

if q.args.start:

q.page['form'] = ui.form_card(box='1 1 12 10', items=[ui.progress('Running...')])

await q.page.save()

seconds = random.randint(1, 6)

# DON'T DO THIS!

# This will make your app unresponsive for some time:

# message = blocking_function(seconds)

# Do this instead:

message = await q.run(blocking_function, seconds)

q.page['form'] = ui.form_card(box='1 1 12 10', items=[ui.message_bar('info', message)])

await q.page.save()

else:

q.page['form'] = ui.form_card(box='1 1 12 10', items=[ui.button(name='start', label='Start')])

await q.page.save()

Tags:  background_tasks